Womanly Virtue(?)

It was obvious that additional material would be necessary to make the story feature film length, but I was intrigued by what they chose to elongate. Much detail was added to the relationship between Marty and Clara in-between them meeting at the Waverly (now Stardust) ballroom and them returning to Marty's home. There was much more detail by ways of them walking down the street, and stopping for a meal at a diner. It seems to me that the most obvious reasons for such additions was the quickness of Marty meeting a girl to bringing her back to his house. When he tries to kiss her while in the kitchen, he states that he wasn't going to try anything (especially since his mother would soon be home), but what was his motivation for bringing her then?(this could also just be 21st century cynicism of male-female relationships)

In addition, while the movie may attempt to heighten Clara's virtue, the virtue of Marty's mother tasks a small assault. When waiting to go into Sunday Mass, the Mother follows much of the same dialogue as the teleplay, telling Marty that Clara doesn't look like a nice girl (mostly because she's "ugly" and not Italian). in the teleplay, when Marty excuses himself to go into church, the mother has a moment of self-reflection as she says to the audience that based on her harsh words, she is becoming as based as her sister. This moment is left out of the film. Without this one sentence, does the mother (and audience) lose this moment of regret and self-awareness? Does her womanly virtue as a mother take a hit, as she schemes against her son's desires for companionship?